<!DOCTYPE html>
<html>
  <head>
    <style>
      div:empty { background: yellow; border: 1px solid black; height: 10px;
                  padding: 0; margin: 0; }
      body > div:not(:empty) { width: 400px; }
    </style>
  </head>
  <body>
    <div style="width: 100px;"></div>
    <div style="width: 50px;"></div>
    <div style="width: 50px;"></div>
    <div style="width: 150px;"></div>
    <div style="width: 150px;"></div>
    <div>
      <div style="width: 200px;"></div>
    </div>
    <div>
      <div style="width: 200px;"></div>
    </div>
    <div>
      <div style="width: 100px;"></div>
    </div>
    <div>
      <div style="width: 200px;"></div>
    </div>
    <div>
      <div style="width: 40px;"></div>
    </div>
    <div style="padding: 0 100px;">
      <div style="width: 200px;"></div>
    </div>
    <div style="padding: 0 100px;">
      <div style="width: 40px;"></div>
    </div>
    <div style="border-width: 0 100px; border-style: solid;
                border-color: transparent;">
      <div style="width: 200px;"></div>
    </div>
    <div style="border-width: 0 100px; border-style: solid;
                border-color: transparent;">
      <div style="width: 40px;"></div>
    </div>
  </body>
</html>
